Modelling redshift-space distortion in the post-reionization $\mathrm{HI}$ 21-cm power spectrum

Abstract

The post-reionization $\mathrm{HI}$ 21-cm signal is an excellent candidate for precision cosmology, this however requires accurate modelling of the expected signal. Sarkar et al. (2016) have simulated the real space $\mathrm{HI}$ 21-cm signal, and have modelled the $\mathrm{HI}$ power spectrum as $P_{\mathrm{HI}}(k)=b^{2}P(k)$ where $P(k)$ is the dark matter power spectrum and $b(k)$ is a (possibly complex) scale dependent bias for which fitting formulas have been provided. This paper extends these simulations to incorporate redshift space distortion and predict the expected redshift space $\mathrm{HI}$ 21-cm power spectrum $P_{\mathrm{HI}}^s(k_{\perp },k_{\parallel })$ using two different prescriptions for the $\mathrm{HI}$ distributions and peculiar velocities. We model $P_{\mathrm{HI}}^s(k_{\perp },k_{\parallel })$ assuming that it is the product of $P_{\mathrm{HI}}(k)=b^{2}P(k)$ with a Kaiser enhancement term and a Finger of God (FoG) damping which has ${\sigma }_p$ the pair velocity dispersion as a free parameter. Considering several possibilities for the bias and the damping profile, we find that the models with a scale dependent bias and a Lorentzian damping profile best fit the simulated $P_{\mathrm{HI}}^s(k_{\perp },k_{\parallel })$ over the entire range $1\le z\le 6$. The best fit value of ${\sigma }_p$ falls approximately as $(1+z{)}^{-m}$ with $m=2$ and $1.2$ respectively for the two different prescriptions. The model predictions are consistent with the simulations for $k<0.3{\mathrm{Mpc}}^{-1}$ over the entire $z$ range for the monopole $P_0^s(k)$, and at $z\le 3$ for the quadrupole $P_2^s(k)$. At $z\ge 4$ the models underpredict $P_2^s(k)$ at large $k$, and the fit is restricted to $k<0.15{\mathrm{Mpc}}^{-1}$.

14 pages, 7 figures, 2 Tables, accepted for publication in MNRAS main journal

References in corpus (18)

• Observational constraints on Cosmic Reionization
• A test of the nature of cosmic acceleration using galaxy redshift distortions
• A discriminating probe of gravity at cosmological scales
• Baryon Acoustic Oscillation Intensity Mapping as a Test of Dark Energy
• Late-time cosmology with 21cm intensity mapping experiments
• Damped Lyman Alpha Systems in Galaxy Formation Simulations
• Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder
• The CMBR fluctuations from HI perturbations prior to reionization
• Possibility of Precise Measurement of the Cosmological Power Spectrum With a Dedicated 21cm Survey After Reionization
• On using visibility correlations to probe the HI distribution from the dark ages to the present epoch I: Formalism and the expected signal
• The Tianlai project: a 21cm cosmology experiment
• Modeling the neutral hydrogen distribution in the post-reionization Universe: intensity mapping
• Estimation of Cosmological Parameters from HI Observations of Post-reionization Epoch
• Cosmological constraints from the redshift dependence of the Alcock-Paczynski effect: application to the SDSS-III BOSS DR12 galaxies
• The Ooty Wide Field Array
• A scale dependent bias on linear scales: the case for HI intensity mapping at z=1
• Cosmological Tests using Redshift Space Clustering in BOSS DR11
• Fisher Matrix Based Predictions for Measuring the z = 3.35 Binned 21-cm Power Spectrum using the Ooty Wide Field Array (OWFA)

Cited by in corpus (3)

• Redshift space distortions of the {\rm HI} 21-cm intensity mapping signal due to the internal motions within galaxies
• Using strong gravitational lensing to probe the post reionization \HI power spectrum
• Combined lensed estimator to probe the post reionization H I power spectrum